Industrial processes involving liquids typically require large liquid storage tanks as one element in such systems. For instance, in food and agricultural processing large liquid storage tanks are often involved to store liquids. Examples include olive oil, or grape juice that is being processed into wine.
Removal of liquids from such large liquid storage tanks often involves a known prior art outlet system known as a “racking arm” tank outlet. A racking arm adds an elongate inlet pipe to a basic valve fitted to a side wall of the tank. This inlet pipe extends into an interior of the liquid storage tank. This elongate inlet pipe has a bend in it so that an entrance of the inlet pipe is spaced away from a central axis of the inlet pipe where it passes through the tank wall. The inlet pipe is mounted to the tank wall in a manner that allows rotation of the inlet pipe, and typically also the valve, relative to the tank wall. When this inlet pipe is rotated, the entrance of the inlet pipe can be adjusted in elevation so that liquids being discharged from the tank can be selectively removed at different elevations within the tank.
Depending on the needs of the operator, the racking arm has the entrance of the inlet pipe positioned where desired within the tank and then the valve is opened to discharge liquid from the desired elevation level of the tank. For instance, an operator might wish to withdraw liquid from near a surface of liquid within the tank, but below this surface to avoid capturing any floating matter. The racking arm can be rotated to place the entrance of the inlet pipe near (but just below) this surface. Similarly, the racking arm can be rotated to be just above sediment near a bottom of the tank. As the amount of liquid within the tank decreases, the racking arm can be rotated to lower the entrance of the inlet pipe to keep it just below the surface.
Numerous problems exist with existing racking arms. Racking arms provide a variety of different loads on the tank wall, depending on the orientation of the racking arm. Because liquid tank design is often optimized to minimize the quantity of material required, the tank wall can be damaged due to these forces exerted by the racking arm upon the tank wall. Also, it can be difficult to know what the orientation of the entrance of the racking arm is when an operator is standing outside of the liquid storage tank. Furthermore, racking arms can be susceptible to leakage if not properly designed. Finally, when handling food grade materials, it is important that the liquid storage tank, and all of the surfaces of the racking arm and associated valves which come into contact with consumable liquids, be sufficiently cleanable to meet desired levels of cleanability and sanitization.